On Jan 28, 2013, at 2:31 PM, Miles Bader wrote:
> Second, a question: Is there a way I can tell OpenImageIO "whatever
> the output format is, use the 'normal' data-type for that format."?
Good question. I think the honest answer is that we don't seem to have
implemented a consistent policy about what happens when a file is opened and
the ImageSpec requests a data type that is not supported by the file format.
Usually, it just picks a good fit among the supported data type. But not all
behave that way -- at least TIFF (I just checked) could outright reject certain
unsupported data types. And there isn't a way to say "give me the default."
So I propose the following rule, which if people approve I can implement in no
time:
1. ImageOutput::open will never fail because of a request for an unsupported
data type; if not supported, it will choose a supported data type that will
lose as little range or precision as possible compared to the original request.
The app, of course, is free to examine output->spec().format, compare it to the
original request, and take action if it couldn't get the data format it
originally requested.
2. If ImageOuput::open() is called with a spec whose format =
TypeDesc::UNKNOWN, the ImageOutput will select a "default" supported data type,
which is informally defined as "the most common configuration of that file type
in the real world, and/or the data type likely to have the widest range of
readers that are able to handle it."
Sound good?
-- lg
--
Larry Gritz
[email protected]
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